Researchers in Adelaide have discovered the mutant gene responsible for epilepsy in women.

It is a ground-breaking discovery and the team from the University of Adelaide and the Adelaide Women's and Children's Hospital has had its findings published today in the journal, Nature Genetics.

The discovery came after scientists, including lead researcher Dr Leanne Dibbens, identified a number of families in which only females suffered from epilepsy and intellectual disability.

Dr Dibbens and her team investigated what genetic defect may be causing the pattern and discovered all these families carried mutants of the same gene.

"We found that these families carry different mutations in the one gene and that when females who carry one good copy and one bad copy of the gene, they are actually affected, whereas males, even when they carry only a bad copy of the gene, they are not affected," she said.

Current research is under way to determine why males are not affected by this gene mutation.

"We have a lead in that we know that there's a related gene on the Y chromosome, and only males carry a Y chromosome, and so we think that this gene is perhaps protecting or rescuing the males in these families from this condition," Dr Dibbens said.

Although the discovery does not promise an immediate cure for the genetic condition, or other epilepsy cases, Dr Dibbens says that it does provide some help for these families.

"The most immediate ramification is that we can now offer genetic counselling to these families that suffer ESMR and people can choose to have pre-natal testing if that's what they desire and make decisions on whether they have daughters with this condition," she said.

"And the wider implications are that we now know that this gene family is involved in epilepsy and intellectual disability and so we'll be looking to see whether this gene or other related genes also play a role in these more common disorders."

The next step, according to Dr Dibbens is to look at a greater sample of patients with other related disorders which are currently little understood.

"We'll now be looking at larger groups of patients with epilepsy, intellectual disability, and a number of the females affected in these families have autistic features and obsessive features and so we'll also be looking at patient cohorts with those features," she said.

"Very little is known about the genetic causes of epilepsy, even the common epilepsies.

"Intellectual disability, we have come a way in understanding causes of that, but in particular, autism and obsessive traits really, very little is known about the genetic causes of those disorders."

Dr Dibbens is confident that while cure or prevention are a long way off, this new research will allow scientists to develop a much greater understanding of how genetics play a role in mental diseases.

"It gives us a chance now to dive in and look at the roles of these types of genes and what roles are playing in the brain and what happens when these processes go wrong and why it leads to autism and obsessive traits," she said.

"It's always difficult to predict where the research will go and what it would lead to, but we hope that it will enable more genetic counselling and possibly treatments and ultimately prevention. But that's a few years off yet."